Everything is made of atoms. An atom is the smallest particle of an element, like oxygen or hydrogen. Atoms join together to form molecules. A water molecule has three atoms: two hydrogen (H) atoms and one oxygen (O) atom.
        
             
        
        
        
Answer: Manholes are usually round, primarily because roundness is the best shape to resist the compression of the earth; covers are round because they are easier to manufacture than square or rectangular shapes, they are easier to move by rolling, and they can't fall into the opening.
Explanation:
 
        
             
        
        
        
Answer:The outer core of the Earth contains a lot of iron in a molten state. As the Earth spins this molten iron moves and creates the Earth's magnetic field. The Earth behaves as if there is a huge bar magnet at its centre. The shape of the field around the Earth is very similar to the field around a bar magnet
Explanation:
 
        
             
        
        
        
Sand dunes would be created due to the mixture falling on each other
x